Question

A man pulls a 50.0 kg box with a rope parallel to the ground he pulls the box 10.0 m about how much work has he done

Answer 1

Your answer is 5000 J

when W(work) = F X  when F= the force and X= the displacment

and F(g) = M a(g) when M= mass and a = the acceleration and in our question
, the force is the gravitational force and a= 9.8 m/S2 we can assume as 10 m/s2

and when we have M= 50 Kg
so by substitution:
F= 50 x 10 = 500 N

and by substitution in work equation: when x = 10 m 
∴ W = 500 x 10 = 5000 j

Answer 2

The weight of the box is (using an approximate value $g=10m/s^2$:
$W=mg=50Kg\cdot10m/s^2=500 N$
Therefore, the man must apply an equal force to pull the box at a height of h=10.0m. The work he has done is equal to the product between this force and the displacement, which is the height h:
$W=Fd=500N \cdot 10m=5000 J$